On combustion, benzoic acid releases 26.38 KJ/g. The bomb calorimeter contained 1.000 g of benzoic acid. The temperature of the calorimeter rises from 24.32 degrees C to 27.05 degrees C?

#a)# What is #DeltaT# of the calorimeter?
#b)# How much heat is absorbed by the bomb calorimeter?
#c)# What is the heat capacity, #C_(cal)#, of the calorimeter, in #"kJ/"^@ "C"#?

2 Answers
Andrea B.
Apr 9, 2018

see below

Explanation:

The absorbed heat is 26,38 KJ. But a calorimeter is made from a contenitor that is heated (#Q= C xx Delta T # and a certain amount of water that is haeted (#Q=m xx Cp xx Delta T). Normally you want to know the C of calorimeter, but to Know it you must know the amount of water...

Truong-Son N.
Apr 9, 2018

A bomb calorimeter is a rigid container that looks as follows:

http://hrsbstaff.ednet.ns.ca/

The benzoic acid is placed into the sample cup inside the bomb, and about #"2 L"# of water submerges the bomb. Thus, the reaction will release heat out into the water to heat up the calorimeter.

#a)#

The change in temperature of the water IS the change in temperature of the calorimeter:

#DeltaT = 27.05^@ "C" - 24.32^@ "C" = ???#

#b)#

The heat absorbed by the calorimeter is the heat released by the reaction, by construction. The massive amount of water will ensure excellent insulation and thus conservation of energy.

Hence, the heat absorbed is

#"26.38 kJ"/cancel"g benzoic acid" xx cancel"1.000 g benzoic acid" = color(blue)("26.38 kJ")#

#c)#

The heat absorbed then gives the heat capacity:

#"26.38 kJ" = C_(cal)DeltaT_(Cal)#

#=> color(blue)(C_(cal) = "26.38 kJ"/(DeltaT_(Cal)) = ??? "kJ/"^@ "C")#

CHALLENGE: Is #C_(Cal)# for the dry device, or for the calorimeter PLUS the water? What two pieces of information are needed to find the heat capacity of the dry device?

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